diff --git a/bitbake/lib/bb/tests/setup.py b/bitbake/lib/bb/tests/setup.py
index c77e750db7..2076613d9b 100644
--- a/bitbake/lib/bb/tests/setup.py
+++ b/bitbake/lib/bb/tests/setup.py
@@ -181,6 +181,11 @@ print("BBPATH is {{}}".format(os.environ["BBPATH"]))
 
 
     def test_setup(self):
+        # unset BBPATH to ensure tests run in isolation from the existing bitbake environment
+        import os
+        if 'BBPATH' in os.environ:
+            del os.environ['BBPATH']
+
         # check that no arguments works
         self.runbbsetup("")